Conventionally, discs or rings used for the display of calendar data (date, day of the week, month, etc.) are held in any one of a plurality of display positions by a jumper (also called a jumper-spring). This jumper constantly presses against a toothing of the disc or ring in question. When changing from one display position to another, the jumper moves away from the toothing, undergoing a rotational motion in an opposite direction to the return force exerted by the spring of the jumper. Thus, the toothing is configured such that torque exerted on the jumper by its spring is minimal in the display positions and, when the disc or ring are driven, the jumper goes through a peak in torque. If it is desired to ensure positioning in the event of shocks, the toothing and the jumper must be designed, in particular the stiffness of the spring, such that the aforementioned peak in torque (maximum torque to be overcome to change the display) is relatively high. It is therefore difficult to dimension calendar discs or rings, in particular date rings, in timepiece movements, since a compromise must be found between guaranteeing the positioning function and minimising the energy consumption of the system when changing from one display position to another. Indeed, the spring cannot be too flexible, because it is necessary to ensure the immobilization of the disc or the ring, but it cannot be excessively stiff, because this would require a very high torque to be provided by a mechanism of the timepiece movement. In this latter case, the disc or ring drive mechanism may be bulky and there is a significant energy loss for the energy source incorporated in the timepiece movement during the driving of the disc or the ring.